Investigation Into the affect of Temperature on the Rate of Carbon Dioxide Production in Yeast.

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Investigation Into the affect of Temperature on the Rate of Carbon Dioxide Production in Yeast

Background Knowledge:

        All organisms respire, and they all produce carbon dioxide, whether it is anaerobic or aerobic respiration. For yeast, respiration is as follows:

Aerobic: C6H12O6 + 6O2→ 6H2O + 6CO2 + ATP

Anearobic: C6H12O6 → 2CO2 + 2C2H5OH

For respiration to occur, there must be a source of food for the organism. In this case, glucose solution was used. The yeast then creates enzymes, which break the glucose up and act as catalysts for respiration. Therefore, the temperature should affect the rate of carbon dioxide because with the increase of heat energy, there is more energy for reactions. However, after a certain temperature, the enzymes will be denatured, and will no longer break down the glucose so no respiration will take place. Although this project will look at the carbon dioxide production in yeast, it can also be used to look at the affect of temperature on enzymes, which is how the results can be explained.

Prediction:

I predict that temperature will affect the rate of carbon dioxide production, by affecting rate of respiration in yeast. I predict that the graph of CO2 volume against time will look like this:

                                              Denaturation point

                                        

                                              Optimum temperature

Volume

(cm3)                                       Therefore, the rate of CO2 production should double

                                       every 10oC, and after the denaturation point it should

                                                drop very rapidly to zero.                

Time (min.)

Detailed scientific knowledge:

        This prediction can be explained with scientific knowledge, which is known about enzymes. Enzymes catalyse reactions in the body, and are made in cells. A catalyst is a chemical, which can start a reaction or increase its rate without being affected by the reaction. This means that an enzyme is completely reusable, as are the yeast beads, which I will use. Generally, all chemical reactions have an increase in rate with extra heat energy, and a decrease in rate with less heat energy, which is temperature. This is explained by the kinetic theory, which states that when particles or atoms have more kinetic energy (directly proportional to the temperature), their velocities will increase, and the probability of a collision occurring will be increased. When a collision occurs, a reaction takes place. Therefore, higher temperature means higher kinetic energy and speed, more reactions and finally more carbon dioxide being produced.

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        All enzymes are specific to their function. They also have a 3D shape with an active site for the catalysing of reactions, which means that each enzyme is specific for the substraite. Enzymes are proteins, and are held together by ionic bonds and strong covalent di-sulphide bonds. These bonds can be easily broken down with heat energy. This means that the protein will have changed shape or denatured, and will no longer have the active sight necessary for it to perform its original function. If it has denatured, the yeast cannot break down the glucose and will not have ...

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